Gravity chute

ABSTRACT

A gravity chute for articles, comprising a chute floor defining a conveying surface, wherein the conveying surface has a conveying angle of inclination pointing in a conveying direction, and comprising at least one side wall which laterally delimits the chute floor, wherein, in addition to the conveying angle of inclination, the conveying surface has a transverse angle of inclination directed transversely to the conveying direction and pointing to a side wall, wherein the side wall, to which the conveying surface runs at a transverse inclination, has first friction properties within a first region extending from the conveying surface to a height h, and has second friction properties within a second region extending above the height h, which differ from the first friction properties, the side wall being recessed within the first region with respect to the second region.

The invention relates to a gravity chute for articles, especially at adelivery end of a sorting conveyor, comprising a chute floor thatdefines a conveying surface, wherein the conveying surface has aconveying angle of inclination pointing in a conveying direction, andcomprising at least one side wall which laterally delimits the chutefloor. Gravity chutes of this kind are used especially in sortingfacilities for sorting parcelled goods as terminals for receiving andstoring the sorted parcelled goods and consist substantially of a flatchute floor arranged at a conveying angle of inclination relative to thehorizontal, and especially transversely to the longitudinal axis of thesorting conveyor, and of two side walls arranged laterally andperpendicularly to the chute floor. If the terminal is also used forstoring the parcelled goods, the inclination of the chute floor or theconveying surface must be made sufficiently large for the parcelledgoods to begin to move from rest against the static friction whennecessary. This is especially important when the chute floor isinterrupted by separating flaps.

In practice, it is frequently required that articles of differentnatures and especially with different surface properties and frictioncharacteristics should be conveyed in the same terminal. This is thecase, for example, whenever cardboard boxes, such as shoe cartons, andarticles packed in plastic bags, such as textiles, are to be sorted in acommon terminal. The angle of inclination of the chute must then beselected such that the article to be conveyed with the greatestcoefficient of friction, which results from the friction pairing betweenthe surface of the article to be conveyed and the surface of thechute—the plastic bag in the example mentioned above—, reliably beginsto move from rest. The consequence of this is that the angle ofinclination for articles of this kind, for which a low coefficient offriction results (such as cardboard boxes), is too large, which causesthose articles to accelerate too rapidly when sliding down, so that whenthey strike an end stop, separating flaps or other articles, they have ahigh impact speed and hence possess a high impact energy, which cancause undesirable damage to the articles to be sorted.

So far, this problem has been solved by active elements, such as brakestraps (belt conveyors), variable inclinations, brake flaps or activebraking strips in the chute floor, though these entail considerableadditional costs.

The problem of the invention consists in improving a gravity chute ofthe generic kind in such a way that it can be ensured that parcelledgoods with different surface properties and hence different coefficientsof friction in the case of friction pairing with the chute are conveyedin a gentle and inexpensive manner.

This problem is solved by a gravity chute according to, for example, agravity chute for articles, comprising a chute floor (14) defining aconveying surface (15), wherein the conveying surface (15) has aconveying angle of inclination (22) pointing in a conveying direction(20), and comprising at least one side wall (16) which laterallydelimits the chute floor (14), wherein, in addition to the conveyingangle of inclination (22), the conveying surface (15) has a transverseangle of inclination (24) directed transversely to the conveyingdirection (20) and pointing to a side wall (16), characterised in thatthe side wall (16), to which the conveying surface (15) runs at atransverse inclination, has first friction properties within a firstregion (17) extending from the conveying surface (15) to a height (h),and has second friction properties within a second region (18) extendingabove the height (h), which differ from the first friction properties,the side wall (16) being recessed within the first region (17) withrespect to the second region (18). The conveying surface is the surfaceof the chute floor or its effective part, which comes into contact witha article conveyed and governs the behaviour of the article with itsfriction properties. In the case of a flat chute floor, the conveyingsurface can be the flat surface of the chute floor. Alternatively, inthe case of a chute floor which is profiled in cross-section, theconveying surface can be formed by a surface of profiling, elevations,ribs or strips running in the conveying direction of the chute floor, onwhich the articles to be conveyed rest.

It may be contemplated that the side wall, at a transverse angle towhich the conveying surface runs, possesses friction properties whichdiffer from the friction properties of the conveying surface and,especially in friction pairing with articles to be conveyed, form acoefficient of sliding friction which differs from a coefficient ofsliding friction formed in friction pairing with the chute floor and inparticular is greater than the latter, at least when the articleconcerned possesses uniform friction properties on its surfaces on whichit touches the lateral surface and the chute floor.

In one variant, it may be contemplated that the side wall, at atransverse angle to which the conveying surface runs, possesses firstfriction properties within a first region extending from the conveyingsurface to a first height, and second friction properties within asecond region extending above the first height, which differ from thefirst friction properties. Different friction properties between the tworegions mean that with an article that is in frictional contact with thefirst region and forms a friction pairing, a different coefficient ofadhesion and coefficient of sliding friction occurs than in the secondregion. By adapting the first height to different articles conveyed withthe gravity chute, different friction forces and hence different brakingeffects on different articles or categories of articles can begenerated, especially when they differ in height.

In a first variant, the first region may recede gradually or more orless continuously with respect to the second region, especially in theform of an arrangement which is not perpendicular to the conveyingsurface, but is inclined at an angle of less than 90°. In special cases,the side wall may be inclined in the first region at a first angle ofless than 90° relative to the conveying surface sein, and may beinclined in the second region at a second angle, likewise less than 90°,relative to the conveying surface, wherein the first angle may besmaller or larger than the second angle.

Alternatively, the side wall may be curved convexly or concavely incross-section relative to the conveying surface, as a result of which,as the height of the side wall above the conveying surface declines, afaster (progressive) or slower (degressive) recession of the firstregion occurs.

In a second variant, it may be contemplated that the side wall isdesigned to be recessed in steps within the first region as a whole withrespect to the second region, especially by a step height of at least 1mm, 2 mm, 3 mm, 5 mm, 8 mm, 10 mm, 15 mm, 20 mm, 30 mm, 50 mm or 100 mm.

It goes without saying that all the variants can be combined, with theside wall running perpendicularly to the conveying surface in the firstor second region, for example, or at an angle of less than 90° thereto,and in the other region at an angle of less than 90° to the conveyingsurface, while in addition the first region as a whole can be designedto be recessed in steps with respect to the second region, wherein thefirst and/or the second regions may in addition be curved convexly orconcavely in cross-section.

The transverse inclination of the conveying surface may be between 5°and 45°, especially between 10° and 30°.

The conveying surface may possess friction properties which, in frictionpairing with articles to be conveyed, generate a coefficient of slidingfriction in the region of 0.05 to 1, especially 0.1 to 0.6, where theconveying surface may consist of metal with or without a coating,stainless steel, plastic, wood, roller strips or a roller track.

It may be contemplated that within the first region, the side wallconsists at least on its surface of metal, plastic, a roller strip orbelt material, especially of wood.

In addition, it may be contemplated that within the second region, theside wall consists at least on its surface of metal, plastic, beltmaterial such as PU or PVC, or a roller strip especially of wood.

It is conveniently contemplated that the side wall and/or the chutefloor are flat and can be arranged perpendicularly to one another.

It is possible to design the gravity chute as a double or multiple chutewith two or more chute floors and side walls arranged side by side.

The invention further relates to a sorting conveyor with a deliverystation on which a gravity chute in accordance with the invention isarranged.

The invention will now be further illustrated with reference to adrawing, in which

FIG. 1 shows a first embodiment of the invention in a schematicperspective view,

FIG. 2 illustrates the conveying angle of inclination of the gravitychute, which is arranged obliquely or transversely to the conveyingdirection of a sorting conveyor,

FIG. 3 shows a second embodiment of the invention,

FIGS. 4 a, b show a third embodiment of the invention, and FIG. 4 cshows another embodiment having an alternative arrangement compared tothat shown in FIG. 4 b, and

FIGS. 5 to 7 illustrate further variants of the invention.

As FIG. 1 shows, the basic idea of the invention is not like aconventional gravity chute, where the chute floor is inclined in theconveying direction, but transversely thereto is aligned horizontally,or not inclined, and whose side walls are perpendicular, but consists inproviding the chute floor with a transverse inclination in addition toits conveying inclination. FIG. 1 schematically shows a sorting conveyor4 moved in a sorting conveying direction 2, which transfers conveyedarticles 8, 10 to a gravity chute 12 at a delivery station 6. Thegravity chute 12 is shaped double, like a roof, and has two chute floors14 arranged in a mirror image of one another and side walls 16 arrangedperpendicularly thereto at their outer longitudinal edges. Each chutefloor 14 defines a conveying surface 15, which has a conveying angle ofinclination 22 pointing in the conveying direction 20 and a transverseangle of inclination 24 pointing transversely to the conveying direction20 (relative to a horizontal plane in each case).

One or more flaps 26 may be arranged in the course of the gravity chutein order temporarily to retain articles taken over from the sortingconveyor 4 and to release them in a controlled way. At a lower end ofthe gravity chute, a stop 28 may be provided which releases the articlesin a controlled manner into a delivery area 30.

For the side walls, it is preferable to choose a material with differentfriction properties relative to the conveying surface, so that thefriction properties of the side wall and the conveying surface differfrom one another.

In particular, it can be beneficial to choose materials with which ahigher coefficient of sliding friction results between the side wall andthe articles to be conveyed than between the chute floor and thearticles. This means that with articles with a comparatively highcoefficient of sliding friction to the conveying surface, acomparatively low perpendicular force to the side wall develops, so thatdespite the higher coefficient of sliding friction at the side wall, thearticles are retarded comparatively less strongly. On the other hand,articles with a comparatively low coefficient of sliding friction to theconveying surface experience a comparatively high perpendicular forcetowards the side wall, so that the high coefficient of sliding frictionbetween the article and the side wall has a comparatively strongerretarding effect.

FIG. 3 shows an embodiment which is suitable for cases in which theconveyed articles are of different heights (either smaller or largerthan a dimension h) above the conveying surface and there is a typicalconnection between the height of an article and the friction propertiesof the article. One example is low articles in the form of plastic bags,e.g. made from polyethylene, which are generally flat and tend topossess higher coefficients of friction, in contrast to cardboard boxes,which generally have a greater height and tend to possess smallercoefficients of friction. The differences in size can be exploited ifthe side wall has different friction properties at different heights,such as metal, plastic, a belt or a roller strip.

In FIG. 3, within a first region 17, which extends to a height h,measured perpendicularly above the conveying surface 15, the side wall16 may have first friction properties and consist on its surface of amaterial which, in friction pairing with most packaging materials (e.g.plastic sheeting, cardboard), leads, for example, to a relatively smallcoefficient of sliding friction. In a second region 18, which extendsabove the height h, the side wall 16 may consist on its surface of amaterial that has second friction properties which, in friction pairingwith most packaging materials, lead to a relatively high coefficient ofsliding friction. As a result, articles 8 in which, in friction pairingwith a conventional gravity chute, there is a relatively smallcoefficient of sliding friction—in this example, cardboard boxes with aheight greater than the height h—come partially or mainly into contactwith a surface whose friction properties lead to a relatively highcoefficient of sliding friction, so that those articles are braked morestrongly than in the state of the art.

Conversely, in the application according to FIG. 3, articles 10 whoseheight is smaller than the height h and whose material, in frictionpairing with a conventional gravity chute leads to a relatively largecoefficient of sliding friction come into contact with a surface withthe first friction properties, which, in friction pairing with thearticle, leads to a relatively small coefficient of sliding friction(smaller than in the case of the articles mentioned previously with aheight>h), so that these parcelled goods, which are braked relativelystrongly in the state of the art, are braked less strongly in accordancewith the invention.

With an appropriate choice of the surface qualities or frictionproperties of the two regions of the side wall, it can be ensured thatarticles reach a similar sliding or conveying speed despite theirdifferent packaging materials.

The embodiment according to FIG. 3 is appropriate whenever flat articleswith high coefficients of sliding friction and high articles with lowcoefficients of sliding friction correlate, based in each case onfriction pairing with the conveying surface. If the relationships arereversed, the friction properties of the side walls also have to bearranged in reverse, as FIG. 4 shows. In a first region 17 up to a firstheight h, the side wall, proceeding from the conveying surface, has asurface with friction properties which, in friction pairing witharticles 10 whose height is smaller than the height h, leads to a firstcoefficient of sliding friction, which is smaller than a secondcoefficient of sliding friction, which results from a friction pairingof articles 8 whose height is greater than the height h and which are incontact with a second region 18 of the side wall, which extends abovethe height h and possesses second friction properties, which differ fromthe first friction properties and lead to the desired higher coefficientof sliding friction.

Since the first region 17 of the side wall, which extends up to theheight h, is arranged to be recessed with respect to the second region18, articles with a height greater than the height h come intofrictional contact exclusively with material with second frictionproperties, whereas, conversely, flat articles with a height smallerthan the height h come into frictional contact exclusively with materialwith first friction properties, as is illustrated in the section viewaccording to FIG. 4 b.

An alternative to the arrangement recessed in steps is shown in FIG. 4c, where an angle of inclination β of the side wall 16 is less than 90°with respect to the conveying surface 15, causing the first region 17 tobe recessed gradually with respect to the second region 18.

FIGS. 5 to 7 schematically illustrate different possible ways ofarranging a gravity chute in accordance with the invention, FIG. 5showing a single embodiment, FIG. 6 showing a double embodiment in theshape of a roof, corresponding to FIGS. 2 to 4, and FIG. 7 showing amultiple arrangement side by side, where the individual chute floors andside walls are parallel to one another in each case.

List of Reference Numerals

-   2 Sorting conveying direction-   4 Sorting conveyor-   6 Delivery station-   8, 10 Article-   12 Gravity chute-   14 Chute floor-   15 Conveying surface-   16 Side wall-   17 First region-   18 Second region-   20 Conveying direction-   22 Conveying angle of inclination-   24 Transverse angle of inclination-   26 Flap-   28 Stop-   30 Delivery area-   h Height-   β Angle of inclination (between 16 and 15).

The invention claimed is:
 1. A gravity chute for articles, comprising achute floor defining a conveying surface, wherein the conveying surfacehas a conveying angle of inclination pointing in a conveying direction,and comprising at least one side wall which laterally delimits the chutefloor, wherein, in addition to the conveying angle of inclination, theconveying surface has a transverse angle of inclination directedtransversely to the conveying direction and pointing to a side wall,characterised in that the side wall, to which the conveying surface runsat a transverse inclination, has first friction properties within afirst region extending from the conveying surface to a height, and hassecond friction properties within a second region extending above theheight, which differ from the first friction properties, the side wallbeing recessed within the first region with respect to the secondregion.
 2. A gravity chute as claimed in claim 1, characterised in thatthe side wall encloses an angle with the conveying surface of less than90°.
 3. A gravity chute as claimed in claim 1, characterised in that theside wall is designed to be recessed within the first region as a wholewith respect to the second region.
 4. A gravity chute as claimed inclaim 1, characterised in that the transverse angle of inclination ofthe conveying surface is between 5° and 45°.
 5. A gravity chute asclaimed in claim 1, characterised in that the conveying surfacepossesses friction properties which, in friction pairing with articlesto be conveyed, generate a coefficient of sliding friction between about0.05 and about
 1. 6. A gravity chute as claimed in claim 1,characterised in that the conveying surface consists of metal, with orwithout a coating, stainless steel, plastic, wood, roller strips or aroller track.
 7. A gravity chute as claimed in claim 1, characterised inthat within the first region, a surface of the side wall comprises oneor more of a metal, a plastic, a belt material, a roller strip, and awood.
 8. A gravity chute as claimed in claim 1, characterised in thatwithin the second region, a surface of the side wall comprises one ormore a of a metal, a plastic, a belt material, a roller strip, and awood.
 9. A gravity chute as claimed in claim 1, characterised in thatthe side wall and/or the conveying surface are flat and are arrangeableperpendicularly to one another.
 10. A gravity chute as claimed in claim1, characterised in that it is designed as a multiple chute with aplurality of chute floors and side walls arranged side by side.
 11. Asorting conveyor, comprising: a delivery station; and a gravity chutefor articles arranged on the delivery station, the gravity chutecomprising a chute floor defining a conveying surface, wherein theconveying surface has a conveying angle of inclination pointing in aconveying direction, and comprising at least one side wall whichlaterally delimits the chute floor, wherein, in addition to theconveying angle of inclination, the conveying surface has a transverseangle of inclination directed transversely to the conveying directionand pointing to a side wall, characterised in that the side wall, towhich the conveying surface runs at a transverse inclination, has firstfriction properties within a first region extending from the conveyingsurface to a height, and has second friction properties within a secondregion extending above the height, which differ from the first frictionproperties, the side wall being recessed within the first region withrespect to the second region.
 12. A gravity chute as claimed in claim 2,wherein the side wall encloses an angle with the conveying surface ofbetween about 45° and about 85°.
 13. A gravity chute as claimed in claim2, wherein the side wall encloses an angle with the conveying surface ofless than about 45°.
 14. A gravity chute as claimed in claim 1, whereinthe side wall is designed to be recessed within the first region as awhole with respect to the second region by a step height (d) of at least1 mm.
 15. A gravity chute as claimed in claim 1, wherein the step height(d) is between about 1 mm and about 50 mm.
 16. A gravity chute asclaimed in claim 14, wherein the step height (d) is at least 50 mm. 17.A gravity chute as claimed in claim 4, wherein the transverse angle ofinclination of the conveying surface is between about 10° and about 30°.18. A gravity chute as claimed in claim 5, wherein the conveying surfacepossesses friction properties which, in friction pairing with articlesto be conveyed, generate a coefficient of sliding friction between about0.1 and about 0.6.